r-ggplot-time-series-with-events

### Set directory
if(.Platform$OS.type == "windows"){
  setwd("c:/R/plots/ggplot-annotated-series")
} else {
  setwd("~/R/plots/ggplot-annotated-series")
}

### Data
data("presidential")
data("economics")

### Packages
library("ggplot2")

### Make dataframe of events
events <- presidential[-(1:3),]
ymin <- min(economics$unemploy)
delta <- 0.05 * diff(range(economics$unemploy))
events$ymin <- ymin
events$timelapse <- c(diff(events$start), Inf)
events$bump <- events$timelapse < 4*370 # ~4 years
offsets <- rle(events$bump)
events$offset <- unlist(mapply(function(l, v) {if(v){(l:1)+1} else {rep(1,l)}}, l = offsets$lengths, v = offsets$values, USE.NAMES = FALSE))
events$ymax <- events$ymin + events$offset * delta
range.x <- range(c(economics$date, events$start))
range.y <- c(0, (max(events$offset)+1)*delta) + ymin

### plot time series
ggplot(data = economics, mapping = aes(x = date, y = unemploy/1000)) +
    geom_line(color = "darkblue") +
    scale_x_date("", limits = range.x) +
    scale_y_continuous(name = "Unemployed (million)") +
    theme(axis.text.x = element_blank()) +
    xlab(NULL)
g1 <- ggplotGrob(last_plot())
### plot events
ggplot(data = events, mapping = aes(x = start)) +
    geom_segment(mapping = aes(y = ymin, xend = start, yend = ymax)) +
    geom_point(mapping = aes(y = ymax), size = 3) +
    geom_text(mapping = aes(y = ymax, label = name),
        hjust = -0.2, vjust = 0.2, size = 6) +
    scale_x_date(limits = range.x) +
    scale_y_continuous(breaks = NULL, limits = range.y) +
    xlab("Years") +
    ylab("")  # creates blank space, unlike ylab(NULL)
g2 <- ggplotGrob(last_plot())


library("grid")
grid.newpage()
g <- rbind(g1, g2, size = "last")
grid.draw(g)

ggsave(g, file = "ggplot-series-annotated.pdf")